Improved flexible silane/Schiff base coating with better biocompatibility for magnesium vascular implants...

Biodegradable magnesium alloys hold promise for next-generation vascular stents, but rapid corrosion in physiological environments can cause fracture failure and adverse inflammatory responses, impeding clinical translation. This study describes a composite coating based on solution-gelation (Sg) and GSH-GPA Schiff base (GP) chemistry. This coating combines a dense siloxane barrier with the release of Schiff base, thereby providing self-healing corrosion protection and immunomodulatory bioactivity. The optimized coating (GP/Sg-0.001) reduces the corrosion current density of ZE21B alloy by three orders of magnitude and maintains structural integrity after 30 days of immersion in Hanks' Balanced Salt Solution, with hydrogen evolution reduced by 79.6% compared to the bare alloy. The coating enables self-healing of barrier function within 72 h upon damage via triggered inhibitor release, while retaining an interfacial adhesion force exceeding 12 N. Schiff base doping markedly improves coating flexibility, as shown by large-bend deformation tests. Beyond corrosion control, this bioadaptive interface selectively promotes endothelial cell adhesion, proliferation and migration, preserves erythrocyte morphology (hemolysis <0.5%), and directs macrophage polarization toward the anti-inflammatory M2 phenotype. This interface promotes the synthesis and release of NO by endothelial cells. This coating combines corrosion protection, flexibility, and bioactivity, enabling magnesium alloys to meet the mechanical demands of complex cerebral microvascular implantation and positioning them as a versatile platform for next-generation cardiovascular implants.